In 2014, I retired the below USB video card. I've replaced with the Plugable USB 3.0 to DisplayPort 4K UHD , which runs fine at 2560x1600.
I use 3 monitors at work and it is awesome. My laptop only drives two monitors so for the 3rd monitor I picked up a USB video card, the EVGA 100-US-UV16A1 . This thing works (*). The device installs drivers automatically and works like a charm on Windows 7. It only supports upto 1600x1200. Also, I don't play games so I can't tell you how well that works, but for reading email and viewing OneNote I can't tell this is a USB video card.
(*) If you're not impressed this thing works, you should be. A back of the envelope bandwidth analysis:
= 1600pixels x 1200pixels x 24 bits per pixel x 30 frames/second
= 1.38 Gbps
Actual USB 2.0 bandwidth: